Update (February 2025): The Ivanpah Solar Electric Generating System, once a milestone in renewable energy, now faces possible closure. Pacific Gas & Electric has agreed to terminate its contracts, citing the higher cost of Ivanpah’s solar-thermal technology compared to photovoltaics. If approved, two of the plant’s three units could shut down by 2026. Southern California Edison is also considering a contract buyout, adding to uncertainty. Environmental concerns, including bird and tortoise deaths from intense solar radiation, have further complicated Ivanpah’s legacy, reflecting the challenges of large-scale clean energy projects.

In the heart of the Mojave Desert, a glittering sea of mirrors sprawls across 3,500 acres, harnessing the relentless desert sun to power homes and businesses across California. As you drive to or from Las Vegas to the West, the facility rises from the desert, resembling an alien spaceport in the distance. From the air, passengers on flights over the desert can easily spot the plant, with its three towering structures gleaming nearly as brilliantly as the sun.

This ambitious undertaking, known as the Ivanpah Solar Electric Generating System, stands as one of the largest concentrated solar power (CSP) plants in the world. Since its completion in 2014, Ivanpah has been celebrated as a major milestone in renewable energy innovation, while also facing considerable scrutiny and challenges. 

The idea behind Ivanpah was born from the vision of BrightSource Energy, led by Arnold Goldman, who was an early pioneer of solar thermal technology. Goldman had previously been involved with Luz International, a company that attempted similar solar ventures in the 1980s. Those early projects struggled due to high costs and limited efficiency, eventually falling victim to the market forces of low fossil fuel prices and a lack of policy support. But by the mid-2000s, the winds had shifted. California, driven by its Renewable Portfolio Standard (RPS), began pushing aggressively for renewable energy sources, setting ambitious targets that mandated utilities procure a large percentage of their electricity from clean sources. This provided fertile ground for a revived effort in concentrated solar power.

With significant financial backing from NRG Energy, Google—which has a strong interest in promoting renewable energy as part of its sustainability goals—and the U.S. Department of Energy (which provided a $1.6 billion loan guarantee), the Ivanpah project broke ground in 2010 and began operation in 2014. By its completion, it had become a landmark renewable energy installation—a bold attempt to demonstrate the viability of CSP technology at scale, with a capacity of 392 megawatts (MW), enough to power around 140,000 homes at peak production.

Ivanpah’s CSP technology differs significantly from the more common photovoltaic (PV) solar panels that typically sprawl across rooftops and solar farms. Instead of directly converting sunlight into electricity, Ivanpah employs a central tower system that uses concentrated solar power to generate steam. The facility harnesses the reflections of 173,500 heliostats (large mirrors) spread across the desert floor, each of which tracks the sun throughout the day using computer algorithms, reflecting sunlight onto a central receiver at the top of Ivanpah’s three 450-foot towers.

Inside these towers, the intense, concentrated sunlight heats water to temperatures of over 1,000°F (537°C). This heat turns water into steam, which drives turbines to generate electricity. This process—turning solar energy into heat, then into steam, and finally into electricity—requires multiple stages of energy conversion, introducing inefficiencies along the way. While innovative, these conversions come with inherent energy losses that ultimately affect overall efficiency. Some of these inefficiencies and energy losses were unanticipated, demonstrating the complexities of scaling concentrated solar power to this level.

The theoretical efficiency of CSP systems like Ivanpah is generally around 15-20%. By comparison, modern PV panels convert sunlight directly into electricity, achieving efficiencies of 15-22%, with some high-end models exceeding 25%. The direct conversion of sunlight by PV systems avoids the multiple stages of transformation needed by CSP, making PV generally more efficient and cost-effective. That is not to say the project was not an unworthwhile effort, just that it has not yet met the early expectations for the technology.

While Ivanpah was a leap forward in solar technology, it has faced several challenges, both technical and environmental. One of the first issues arose in the initial years of operation: the plant produced less electricity than anticipated, often falling short of its projected targets. This shortfall was attributed to a combination of technical complications, lower-than-expected solar irradiance, and operational adjustments as engineers sought to optimize the plant’s complex systems.

In addition, Ivanpah relies on natural gas to preheat its boilers in the early morning or during cloudy weather, ensuring the turbines are ready to operate as soon as the sun provides enough energy. This auxiliary use of natural gas has sparked criticism, with some questioning whether Ivanpah can truly be considered a clean, renewable energy source. While the natural gas usage is minimal relative to the plant’s total output, it highlights a practical limitation of CSP systems, which need to overcome the intermittent nature of sunlight.

Environmental impacts have also drawn attention. Ivanpah’s vast array of mirrors produces a phenomenon known as solar flux, a concentrated field of heat that can reach temperatures high enough to injure or kill birds flying through it. Dubbed ‘streamers,’ because of the smoke that comes from their wings when they burn in midair, birds that enter this concentrated beam often die. (Here’s a video about it.) A report from the California Energy Commission refers to what they call a “megatrap,” where birds are drawn to insects that are attracted to the intense light emitted from the towers. This unintended effect on wildlife has been a significant concern for conservation groups, prompting Ivanpah to work on mitigation measures, including testing visual deterrents to keep birds away.

Moreover, the sheer size of Ivanpah, covering a significant area of desert land, has raised concerns about the impact on local ecosystems. The Mojave Desert is a delicate environment, and constructing such a large facility inevitably affected the flora and fauna, prompting debates about whether renewable energy projects should be balanced with efforts to preserve pristine habitats.

Ivanpah is just one of several large-scale CSP projects around the globe. Another notable example is the Noor Ouarzazate Solar Complex in Morocco, which is one of the largest CSP installations in the world. The Noor Complex uses both parabolic trough and solar tower technologies and, crucially, incorporates molten salt to store heat, allowing it to generate electricity even after the sun has set. The use of molten salt offers several advantages over water-based systems like Ivanpah. Molten salt can retain heat for longer periods, enabling the plant to continue generating power during periods of low sunlight or even after sunset, which greatly improves grid reliability and helps balance energy supply with demand.

Similarly, the Crescent Dunes project in Nevada was another attempt to utilize molten salt for energy storage. It initially showed promise but struggled with technical setbacks and eventually ceased operation in 2019 due to persistent issues with the molten salt storage system and failure to meet performance expectations. The technology, although innovative, struggled with high maintenance costs, particularly with the heliostat mirrors and salt storage tanks. The company behind Crescent Dunes, SolarReserve, went bankrupt after being sued by NV Energy for failing to meet its contractual obligations.

Despite these setbacks, the project has not been fully decommissioned. ACS Cobra, the Spanish firm involved in its construction, now operates the plant at reduced capacity, mainly delivering energy during peak demand at night. Although Crescent Dunes has never reached its full potential, it continues to produce some electricity for Nevada’s grid, albeit far below the originally planned levels.

Crescent Dunes underscored the challenges associated with large-scale CSP projects, particularly the difficulty of balancing complexity, maintenance, and operational costs. However, the use of molten salt in Crescent Dunes demonstrated the significant potential for improving CSP efficiency through effective thermal storage, highlighting a critical advantage over water-based systems like Ivanpah that lack extensive storage capabilities.

While CSP holds the advantage of potential energy storage—something PV cannot inherently achieve without additional batteries—PV technology has seen a steep decline in cost and significant improvements in efficiency over the past decade. This rapid evolution has made PV panels more attractive, leading to widespread adoption across both utility-scale and residential projects. Hybrid projects, like Phase IV of the Mohammed bin Rashid Al Maktoum Solar Park in Dubai, are now combining PV and CSP technologies to maximize efficiency and output, utilizing each technology’s strengths.

Ivanpah remains operational, continuing to contribute renewable energy to California’s grid.

Governor Gavin Newsom has commented on the importance of renewable projects like Ivanpah in meeting California’s ambitious clean energy goals. Newsom has praised Ivanpah as a vital component of the state’s effort to transition away from fossil fuels, emphasizing the need for innovative projects to meet California’s target of achieving 100% renewable energy by 2045. He has highlighted the symbolic value of Ivanpah, not only as a source of clean energy but as a testament to California’s leadership in renewable technology and environmental stewardship. Its story is one of both ambition and caution, highlighting the promise of concentrated solar power as well as its practical and environmental limitations. In many ways, Ivanpah serves as a testbed for CSP technology, providing valuable insights into the challenges of scaling such systems to utility-level production. It has also sparked discussions on the role of CSP compared to other forms of renewable energy, especially as battery technology advances to address PV’s storage challenges.

While CSP is unlikely to overtake PV in terms of widespread adoption due to its complexity and cost, it still has a role to play, particularly in regions with intense sunlight and a need for energy storage. The lessons learned at Ivanpah—both the successes and the setbacks—will inform the next generation of solar projects, driving innovation and helping policymakers, engineers, and investors make more informed decisions about the future of renewable energy infrastructure.

California’s solar and renewable energy installations have seen remarkable success in recent years, as the state continues to push toward its ambitious goal of 100% clean electricity by 2045. In 2024, California achieved several milestones that highlight the effectiveness of its clean energy initiatives. For example, the state has more than 35,000 MW of renewable energy capacity already serving the grid, with 16,000 MW added just since 2020. A key component of this growth is the rapid expansion of battery storage, which has become essential for balancing the grid, especially during peak demand times when solar power diminishes in the evening. In 2024 alone, battery storage capacity grew by over 3,000 MW, bringing the total to more than 13,000 MW—a 30% increase in just six months​

​In addition to storage, new solar projects like the Blythe Solar Power Project, which generates 485 MW of photovoltaic power and adds 387 MW of battery storage, are powering over 145,000 homes, further demonstrating California’s leadership in clean energy development​. This continued investment not only strengthens the grid but also ensures resilience during extreme weather events, which have become more frequent due to climate change.

Despite these successes, California still has a long way to go. The state will need to bring an additional 148,000 MW of renewable resources online by 2045 to fully meet its goals​. However, with the state’s rapid advancements in storage technology, solar capacity, and governmental support, California is well on its way to achieving a cleaner, more sustainable energy future.

Beyond its role in renewable energy, Ivanpah has also found itself at the intersection of technology and art. One notable example is when Google arranged the mirrors at Ivanpah to create a tribute to Margaret Hamilton, the pioneering computer scientist who led the software engineering efforts for the Apollo space missions. This artistic alignment of mirrors highlighted Ivanpah’s versatility—not just as an engineering marvel for energy generation but also as a symbol of human achievement. The intricate choreography of heliostats to form an image visible from above served as a powerful visual homage, merging art, science, and technology in a striking way. Such projects have helped broaden the cultural significance of Ivanpah, presenting it not only as a source of renewable energy but also as an inspirational platform that celebrates human creativity and accomplishment.

The next time you’re driving to Vegas and spot the three massive, sun-like objects glowing in the desert, give a thought to the immense power—and challenges—of harnessing the sun’s energy in such a dramatic way.

by Erik Olsen